People in today's world rely heavily on a wide variety of electrical devices. Almost all of these devices draw power ultimately from a commercial source, usually delivered to the user through a wall outlet or socket. Accordingly, the electrical devices are fitted with a plug. Unfortunately, if the device is moved from location to location, the prongs of the plug extend outward and can be difficult to pack (or store) or can catch on clothing, packaging material and the like.
One particularly large class of portable electrical devices available today makes use of rechargeable batteries. For many devices, such as portable phones, video games, calculators, and the like, a battery is or can be fitted within the device itself. For some devices, the battery can be removed easily, while in other devices, the battery is not designed to be removed.
A variety of battery chargers are available for use with such devices. In general, a manufacturer provides a battery charger specifically designed for use with one or more products. Traditionally, the battery chargers are bulky devices, often weighing 500 grams or more. A typical charger includes a plug for insertion into a wall socket, and if the plug is moved, a problem may arise with leaving the prongs exposed. The specific size of the battery charger is determined by a number of factors, including power to be delivered during recharging and the presence or absence of special circuitry, for example to monitor the state of charge of a battery.
In one typical configuration, a power cord goes between the power supply and a wall socket, with a second power cord extending between the power supply and the device containing the battery. In another typical configuration, the power supply is built into a large module which is designed to be plugged directly into a wall socket. A single cord connects the power supply to the battery.
In some devices, a cradle or receptacle is built into a casing which is designed to accommodate a device including a battery, or sometimes a removable battery or battery pack. Many cellular or cordless phones are designed to mate with such a cradle in a recharging station. Many batteries for computers or power tools are also designed to mate with such a cradle or recharging station. The power supply may be incorporated in the charging station or may be separate.
A few plug devices have been designed with a plug or prongs which fold into a casing. This is particularly helpful for a device which may be moved from location to location or which is incorporated into the body of a device. For example, some rechargeable flashlights include the collapsible prongs which can be rotated into a position extending out from the body of the flashlight and plugged directly into a wall socket or extension cord. In another example, some telephone charging stations include a cradle for the telephone and a rotatable plug which can be extended into position for plugging into a wall socket, or collapsed into a space in the shell of the charging station, particularly so that a user may slip a charging station into a pocket, a briefcase, or other container, or simply for storage, as in a drawer.
Presently available collapsible plug devices suffer from various problems which make them inconvenient or even dangerous to use. In particular, the rotatable plug has only a weak spring holding the plug in position. It does not take much effort to collapse the plug, which may cause the plug to partially or completely pull out of a wall socket. This can compromise the electrical connection to the point that the plug no longer is in electrical contact with source current. In some circumstances, this may expose the prongs of the plug in such a way that a person, or even an animal, might come into contact with live current, thereby causing bodily harm. In addition, a collapsing plug might pinch the user.
The new device of this invention overcomes these problems by providing a plug device which can be securely maintained in the extended position but folded easily to a compact, collapsed position.